x86/tx_float: remove HAVE_AVX2_EXTERNAL checks

It'll always be enabled.
Thanks, nasm.

libavutil/x86/tx_float.asm

@@ -1517,11 +1517,9 @@ FFT_SPLIT_RADIX_FN avx, 0
 FFT_SPLIT_RADIX_FN avx, 1
 FFT_SPLIT_RADIX_FN fma3, 0
 FFT_SPLIT_RADIX_FN fma3, 1
-%if HAVE_AVX2_EXTERNAL
 FFT_SPLIT_RADIX_FN avx2, 0
 FFT_SPLIT_RADIX_FN avx2, 1
 %endif
-%endif
 
 %macro FFT15_FN 2
 INIT_YMM avx2
@@ -1581,7 +1579,7 @@ cglobal fft15_ %+ %2, 4, 10, 16, ctx, out, in, stride, len, lut, tmp, tgt5, stri
     RET
 %endmacro
 
-%if ARCH_X86_64 && HAVE_AVX2_EXTERNAL
+%if ARCH_X86_64
 FFT15_FN 0, float
 FFT15_FN 1, ns_float
 %endif

libavutil/x86/tx_float_init.c

@@ -282,7 +282,6 @@ const FFTXCodelet * const ff_tx_codelet_list_float_x86[] = {
     TX_DEF(fft_sr_ns, FFT, 64, 2097152, 2, 0, 352, b8_i2, fma3,  FMA3,  AV_TX_INPLACE | FF_TX_PRESHUFFLE,
            AV_CPU_FLAG_AVXSLOW),
 
-#if HAVE_AVX2_EXTERNAL
     TX_DEF(fft15, FFT, 15, 15, 15, 0, 320, factor_init, avx2, AVX2,
            AV_TX_INPLACE, AV_CPU_FLAG_AVXSLOW),
     TX_DEF(fft15_ns, FFT, 15, 15, 15, 0, 384, factor_init, avx2, AVX2,
@@ -304,7 +303,6 @@ const FFTXCodelet * const ff_tx_codelet_list_float_x86[] = {
 
     TX_DEF(mdct_inv, MDCT, 16, TX_LEN_UNLIMITED, 2, TX_FACTOR_ANY, 384, m_inv_init, avx2, AVX2,
            FF_TX_INVERSE_ONLY, AV_CPU_FLAG_AVXSLOW | AV_CPU_FLAG_SLOW_GATHER),
-#endif
 #endif
 
     NULL,